There has been a rumour that VMware circulating that are going to move to a per VM Guest licensing model rather than the traditional Host based licenses. Well it looks like the first move to this has been taken, I was having a conversation with a friend about an issue they were having with a VDI Proof of Concept (POC) they were running.

So what exactly was this issue, well one of his co-workers was trying to vMotion a running XP desktop from host one to host two but was receiving the following message

Error: There are not enough licenses…

On first look this seems an odd message, as both hosts are licensed with an Enterprise level version of ESX, so migration should have been possible. However when we delved deeper we found that both hosts were licensed with the 10 user VMware for Desktop version and both hosts were running 10 desktops, we shut down a guest on the target host and tried the migration again and this time it was successful.

This is a worrying situation here is that the environment was licensed for 20 desktops. Further to that you would expect a Host to be able to run more than 10 guests, this is not a good situation to be in if you are relying on HA for protection on a host failure.

The long and short of this is that this is a downside of Host based licensing. This situation would not have happened with the VMware Virtual Infrastructure 3 FlexLM license server as the Cluster would have known that it was licensed for 20 guests over the cluster and not 10 per host. If VMware is going down this track, then they had better sort out some form of pooling for the licenses. My personal view is that the return to host-based licensing was a retrograde step and not really in line with the vision for an enterprise platform, it smells more of tactical deployments rather than a strategic view.

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Tom Howarth is an IT Veteran of over 20 years experience and is the owner of PlanetVM.Net Ltd, Tom is a moderator of the VMware Communities forum. He is a contributing author on VMware vSphere(TM) and Virtual Infrastructure Security: Securing ESX and the Virtual Environment, and the forthcoming vSphere a Quick Guide. He regularly does huge virtualization projects for enterprises in the U.K. and elsewhere in EMEA. Tom was Elected vExpert for 2009 and each subsequent year thereafter.